Various processing methods are adopted for press machines. One of the processing methods is an oscillation processing method of molding a workpiece by applying a pressing load smaller than a regular pressing load to the workpiece while oscillating a slide. This oscillation process is carried out, for example, by alternately repeating what is termed as a drive-in operation and what is termed as a return operation. The drive-in operation is that in which a rotation of a crank shaft in a direction lowers a slide, and thereby a punching mold drives a workpiece into a die mold. The return operation is that in which a rotation of the crank shaft in the other direction raises the slide, and thereby the punching mold is returned upward.
A press machine of carrying out the oscillation process includes: a servo motor for raising and lowering the slide by rotating the crank shaft; and a controller for doing things such as controlling this servo motor. A CRT touch panel display is connected to the controller. Through this CRT touch panel display, motion data are inputted by the operator's input operation. A motion datum includes, as input items, a height position and speed at which the slide starts an oscillation process, a height position and speed at which the slide carries out the first drive-in operation, a height position and speed at which the slide carries out the first return operation, a height position and speed at which the slide carries out the second drive-in operation, a height position and speed at which the slide carries out the second return operation, . . . , a height position and speed at which the slide carries out the (N−1)th drive-in operation, a height position and speed at which the slide carries out the (N−1)th return operation, a height position and speed at which the slide carries out the Nth drive-in operation, a height position and speed at which the slide carries out the Nth return operation.
The controller includes a CPU, a ROM, a RAM and the like. The CPU includes: a function as a motion pattern generator for generating a motion pattern of the slide on the basis of a motion datum inputted through the CRT touch panel display; and a function as a motor controller for controlling the servo motor on the basis of the motion pattern generated by the motion pattern generator.
Once the motion datum is inputted through the CRT touch panel display by the operator's input operation, the motion pattern generator generates the motion pattern of the slide on the basis of the motion datum inputted through the CRT touch panel display. Thus, the motor controller controls the servo motor on the basis of the motion pattern generated by the motion pattern generator. This makes it possible for the press machine to alternately repeat the drive-in operation and the return operation, and to thereby apply the oscillation process to the workpiece using cooperation between the punching mold and the die mold while oscillating the slide.
It should be noted that a prior art concerning the present invention is disclosed by Japanese Patent Application Laid-open Publication No. Hei. 11-226798 (Patent Document 1).
The press machine for carrying out the oscillation process generates the motion pattern on the basis of the motion datum including, as input items, the height position and speed at which the slide carries out each drive-in operation as well as the height position and speed at which the slide carries out each return operation, in addition to the height position and speed at which the slide starts the oscillation process as well as the height position and speed at which the slide ends the oscillation process. For this reason, as the drive-in operations and the return operations are increased in number, or as the number of times the slide is oscillated is increased, the number of input items included in the motion datum is increased. As a result, it takes a longer time for the operator to input the datum, and this makes the operator's work complicated. Particularly in a case where, as an input item included in the motion datum, the height position at which the slide starts the oscillation process needs to be changed, the motion datum has to be modified to a large extent. This makes the operator's work more complicated.
It should be noted that, because the press machine applies the oscillation process to the workpiece by alternately repeating the drive-in operation linked with the slide's descent and the return operation linked with the slide's ascent, it takes long for the press machine to carry out the oscillation process.
The present invention has been made for the purpose of solving the foregoing problems. A first object of the present invention is to provide a press machine, a crank press machine and an oscillation processing method adopted for the machines, which make it possible to check the increase in the number of input items included in a motion datum, and thus to check the increase in time needed for an operator to input the datum, as well as to accordingly enhance the operator's work efficiency.
A second object of the present invention is to provide a press machine, a crank press machine and an oscillation processing method adopted for the machines, which are capable of holding a slide's oscillation frequency virtually constant during an oscillation process, and thereby holding a pressing load virtually even, as well as of improving the precision with which a workpiece is molded.
A third object of the present invention is to provide a press machine, a crank press machine and an oscillation processing method adopted for the machines, which are capable of carrying out an oscillation process while oscillating the slide without the return operation linked with the slide's ascent. Thus, time needed for the oscillation process is reduced, accordingly enhancing the productivity.
A fourth object of the present invention is to provide a press machine, a crank press machine and an oscillation processing method adopted for the machines, which are capable of eliminating the abrasion between the punch mold and the workpiece, of checking the wear of the mold, and thereby extending the life of the mold. The provided press machine, the crank press machine and the oscillation processing method adopted for the machines, are also capable of checking the workpiece from being damaged, and thereby of improving the processing quality.